Embodiments of the inventive concept relate to a semiconductor device, and more particularly, relate to a pulse amplitude modulation transmitter and a pulse amplitude modulation receiver.
There is an increasing demand on transmitting a large amount of data at high speed as mobile devices are more extensively deployed and as Internet traffic rapidly increases. However, it is difficult to satisfy the demand for transmitting a large amount of data at high speed using a signaling technique that is based on non-return to zero (NRZ) encoding. In recent years, a pulse amplitude modulation (e.g., PAM4) signaling scheme has been actively developed as an alternative to NRZ signaling for transmitting a large amount of data at high speed.
The simplest way to improve energy efficiency in transmitting data by using a pulse amplitude modulation scheme is multi-bit signaling. It is known that an existing current-mode PAM4 transmitter consumes about four times more current than a voltage-mode PAM4 transmitter. The voltage-mode PAM4 transmitter has performed impedance matching by using an on-chip inductor. However, the range of data transmission speed of a transmitter is limited when using the on-chip inductor. Also, a relatively large chip area is needed to implement the transmitter. In addition, a general PAM4 receiver consumes current in a state where data are not received. When a decision feedback equalizer (DFE) for the PAM4 receiver is implemented, issues associated with RC loading, such as a speed limit and an increase in current, may occur.